[openib-general] [PATCH/RFC 1/2] IB: Return "maybe_missed_event" hint from ib_req_notify_cq()

[Roland Dreier]

 > I run out of ideas why losing 2/3 of the throughput and got 476 trans/s. So
 > I assumed there was always a missed event, then ipoib would stay in its
 > napi poll within its scheduled time. That's why it helps. This is really a
 > hack, doesn't address the problem. It sacrificed cpu utilization and gained
 > the performance back. I need to understand how ehca reports missing event,
 > there might be some delay there?

It's entirely possible that my implementation of the missing event
hint in ehca is wrong.  I just guessed based on how poll CQ is
implemented -- if the consumer requests a hint about missing events,
then I lock the CQ and check if its empty after requesting
notification.

I looked over my code again, and I don't see anything obviously wrong,
but it's quite possible I made a mistake that I just can't see right
now (like reversing a truth value somewhere).  Someone who knows how
ehca works might be able to spot the error.

 - R.